SPIRAL DEFECT CHAOS IN A MODEL OF RAYLEIGH-BENARD CONVECTION

A numerical solution of a generalized Swift-Hohenberg equation in two dimensions reveals the existence of a spatiotemporal chaotic state com prised of a large number of rotating spirals. This state is observed f or a reduced Rayleigh number epsilon = 0.25. The power spectrum of the pattern is isotropic, and the spatial correlation function decays exp onentially, with an estimated decay length xi almost-equal-to 2.5lambd a(c), where lambda(c) is the critical wavelength near the onset of con vection. Our study suggests that this spiral defect state occurs for l ow Prandtl numbers and large aspect ratios.